1. Technical Field
The present invention relates to a moisture-absorbing resin composition, and to a molded product of the composition. More particularly, the present invention relates to a moisture-absorbing resin composition exhibiting higher moisture absorbency and higher moisture absorption rate, as compared with conventional resin compositions, and also exhibiting adhesion; and to a molded product produced from the composition.
2. Background Art
Hitherto, upon packaging of drugs, foods (including healthy foods), cosmetics, semiconductor products, machine parts, etc., a desiccant formed of, for example, silica gel, calcium chloride, calcium oxide, or zeolite has been used for the purpose of preventing degradation of such a commercial product due to moisture absorption.
When such a desiccant in the form of particles or powder is used for the aforementioned purpose (i.e., protection of a commercial product from moisture absorption), the particulate or powdery desiccant is packed with paper or nonwoven fabric or sealed into a container or the like, and the packed or sealed desiccant is packaged together with the commercial product. Therefore, there often arise problems, including breakage of the packing material used for packing of a desiccant, and accidental swallowing of a desiccant when the desiccant is packaged together with a food.
Thus, there has been proposed means for solving such a problem, which employs a molded product formed through molding of a mixture of a thermoplastic resin and fine desiccant particles.
For example, Patent Document 1 discloses a moisture-absorbing container characterized by being formed of a polyolefin resin layer (A) exhibiting moisture-proof property, and a polyolefin resin composition layer (B) which contains an inorganic compound having moisture absorbency and which is provided inside the layer (A). Patent Document 2 discloses a moisture-absorbing composition and a molded product thereof, the composition being prepared through kneading of a water-insoluble thermoplastic resin with synthetic zeolite, wherein at least a portion of the water-insoluble thermoplastic resin is a water-vapor-transmitting resin having a water vapor transmission rate (40° C., 90% RH, thickness: 100 μm) of 100 g/(m2·24 hr) or more. The humidity in such a moisture-absorbing container can be maintained at a low level for a long period of time.
A container formed of the aforementioned moisture-absorbing resin layer is used for storing a product whose performance is likely to be impaired through moisture absorption (e.g., a blood glucose level sensor or a urine test strip). When such a product is stored in the container, upon use of the product, the container is repeatedly opened and closed for removal of the product therefrom. In such a case, once the container is opened (uncovered), moisture-containing air enters the container. Therefore, the container is required to have moisture absorbency; i.e., ability to reduce the humidity in the container to a low level within a short period of time after closing of the container. In view of the foregoing, demand has arisen for a moisture-absorbing resin composition or a molded product thereof used for such a container; i.e., a resin composition exhibiting high moisture absorbency and high moisture absorption rate, or a molded product of the composition.